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Enforce network policy for Istio

Big picture

Calico integrates seamlessly with Istio to enforce network policy within the Istio service mesh.

Value

Calico network policy for Istio lets you enforce application layer attributes like HTTP methods or paths, and cryptographically secure identities for Istio-enabled apps.

Concepts

Benefits of the Istio integration

The Calico support for Istio service mesh has the following benefits:

• Pod traffic controls

  Lets you restrict ingress traffic inside and outside pods and mitigate common threats to Istio-enabled apps.

• Supports security goals

  Enables adoption of a zero trust network model for security, including traffic encryption, multiple enforcement points, and multiple identity criteria for authentication.

• Familiar policy language

  Kubernetes network policies and Calico network policies work as is; users do not need to learn another network policy model to adopt Istio.

See Enforce network policy using Istio tutorial to learn how application layer policy provides second-factor authentication for the mythical Yao Bank.

Before you begin

Required

• Calico is installed
• calicoctl is installed and configured

Istio support

Following Istio versions have been verified to work with application layer policies:

• Istio v1.10.2
• Istio v1.9.6
• Istio v1.7.4

Istio v1.6.x and lower are not supported.

Although we expect future minor versions to work with the corresponding manifest below (for example, v1.9.7 or v1.10.3), manifest compatibility depends entirely on the upstream changes in the respective Istio release.

How to

1. Enable application layer policy
2. Install Istio
3. Update Istio sidecar injector
4. Add Calico authorization services to the mesh
5. Add namespace labels

Enable application layer policy

To enable the application layer policy, you must enable the Policy Sync API on Felix cluster-wide.

In the default FelixConfiguration, set the field, policySyncPathPrefix to /var/run/nodeagent:

calicoctl patch FelixConfiguration default --patch \
   '{"spec": {"policySyncPathPrefix": "/var/run/nodeagent"}}'

Install Istio

1. Verify application layer policy requirements.
2. Install Istio using installation guide in the project documentation.

curl -L https://git.io/getLatestIstio | ISTIO_VERSION=1.10.2 sh -
cd $(ls -d istio-* --color=never)
./bin/istioctl install

For Istio v1.7.4, Istio can be installed in both strict mode or permissive mode. Application layer policies work with both Istio in strict or permissive mode. When dealing with mTLS traffic, Calico will cryptographically verify identity while making an authorization decision. When Calico receives plain-text instead, it will fall back on using IP addresses to verify identity.

Strict mode is strongly suggested when creating a new cluster. For example, to install Istio in strict mode:

./bin/istioctl install --set values.global.controlPlaneSecurityEnabled=true

next, create the following PeerAuthentication policy.

Replace namespace below by rootNamespace value, if it’s customized in your environment.

kubectl create -f - <<EOF
apiVersion: security.istio.io/v1beta1
kind: PeerAuthentication
metadata:
  name: default-strict-mode
  namespace: istio-system
spec:
  mtls:
    mode: STRICT
EOF

Update Istio sidecar injector

The sidecar injector automatically modifies pods as they are created to work with Istio. This step modifies the injector configuration to add Dikastes (a Calico component), as sidecar containers.

1. Follow the Automatic sidecar injection instructions to install the sidecar injector and enable it in your chosen namespace(s).
2. Patch the istio-sidecar-injector ConfigMap to enable injection of Dikastes alongside Envoy.

• Istio v1.10.x
• Istio v1.9.x
• Istio v1.7.x

curl https://docs.projectcalico.org/manifests/alp/istio-inject-configmap-1.10.yaml -o istio-inject-configmap.yaml
kubectl patch configmap -n istio-system istio-sidecar-injector --patch "$(cat istio-inject-configmap.yaml)"

curl https://docs.projectcalico.org/manifests/alp/istio-inject-configmap-1.9.yaml -o istio-inject-configmap.yaml
kubectl patch configmap -n istio-system istio-sidecar-injector --patch "$(cat istio-inject-configmap.yaml)"

curl https://docs.projectcalico.org/manifests/alp/istio-inject-configmap-1.7.yaml -o istio-inject-configmap.yaml
kubectl patch configmap -n istio-system istio-sidecar-injector --patch "$(cat istio-inject-configmap.yaml)"

Add Calico authorization services to the mesh

Apply the following manifest to configure Istio to query Calico for application layer policy authorization decisions.

• Istio v1.10.x and v1.9.x
• Istio v1.7.x

kubectl apply -f https://docs.projectcalico.org/manifests/alp/istio-app-layer-policy-envoy-v3.yaml

kubectl apply -f https://docs.projectcalico.org/manifests/alp/istio-app-layer-policy-v1.7.yaml

Add namespace labels

You can control enforcement of application layer policy on a per-namespace basis. However, this only works on pods that are started with the Envoy and Calico Dikastes sidecars (as noted in the step, Update Istio sidecar injector). Pods that do not have the Calico sidecars, enforce only standard Calico network policy.

To enable Istio and application layer policy in a namespace, add the label istio-injection=enabled.

kubectl label namespace <your namespace name> istio-injection=enabled

If the namespace already has pods in it, you must recreate them for this to take effect.

Note: Envoy must be able to communicate with the istio-pilot.istio-system service. If you apply any egress policies to your pods, you must enable access. For example, you could apply a network policy.

Above and beyond

• Enforce network policy using Istio tutorial
• Use HTTP methods and paths in policy rules